Hey everyone!  Thanks to all who have kindly offered input thus far, and kindest thoughts to those who would like to offer their 2 cents on my hypothetical topper set-up.  I had mentioned earlier that I was thinking about ordering a convoluted latex topper, well, I went ahead and did so.  I love how cushy it feels, but it's still too firm for me, causing mild Fibro pain.  I was wondering if it would help to put a memory foam topper over the latex topper, and I was thinking that a 2" 3 lb. Perfect Comfort memory foam topper from absolutecomfortonsale.com might do the trick.  

So how does that sound?  Soft enough to appease my hypersensitive nerve endings, do you think?  If you have an alternative suggestion, please feel free to toss it out there!  

FWIW ... when I was laying on lots of beds, one of them was the Simmons NxG 575. It has 3/4" latex (quilted) over 2" NxG memory foam over 3" 28 ild Talalay latex over pocket coils. When I lay on it I have to say that it was probably the softest feeling mattress I lay on. It was like slowly sinking in to the mattress ... but not too far ... not like "poly softness" ... and not like just memory foam either. I didn't want to go in that direction (it was just curiosity) but my initial impression was very nice.

I don't know how thick your latex is or what it is on top of but it may be worth seeing if you can find one of these to test it out to get an idea of what latex/visco/latex can feel like. I'm not a big fan of sleeping right on memory foam (doesn't sound like you are either) but if I went in that direction it would be with a thin layer (1" or so) of latex over it and a thicker layer of latex under it similar to the NxG. Sandman has played with this a lot as well and could probably give you a lot of feedback on what the different latex/visco combinations feel like.

Phoenix

I would suggest taking a look at using a 14 ILD latex (perhaps in 1" increments) to give the softness of memory foam but without the downside of some memory foam or poly foam.  I know Sleeps Like a Bear has one, not sure who else might have one.

Do you know the firmness of your convoluted latex?  Where did you buy?

I think adding a little memory foam can work for many people.   The main risk is that it provides minimal support, in that you sink in a fair amount as it warms up.  So, sensitive back people often have problems.

Personally I would not buy 3lb memory foam, because you will get a bit better support factor in higher density foam.  I would prefer at least 4lb, and ideally 5lb or higher.  Of course it will depend on how it is made, what you weigh, etc.  Higher density also lasts longer - or at least that is what most people say. 

2" might be okay or might be too much.  I think okay on a reasonably firm surface.  If you latex is already somewhat soft, then trying 1" might be better.  If it does not do enough, then you can always add 1 more inch.  I find that changing 1" can make a material difference, if you are fairly sensitive.

Overstock is one of the few places that has 1" in 4lb. (mem-cool) and Sensus (5lb).  The mem-cool is a bitter softer and plusher, the Sensus is firmer and more supportive (and possibly hotter).  Hard to say what you would prefer without trying.  I don't think you can return from overstock.  Pretty good pricing though.

Foamorder has 1", 2", 3" 4lb and 5.3lb.  They rate the 5.3 medium soft, and the 4lb medium.  90 day trial on the 5.3lb.  I have not tried either, but I have thought about trying the 5.3.

As Sall mentioned, 14ILD latex from sleeplikeabear is another alternative.  Probably less plush and body molding than memory foam, but probably higher support.  I think they have a 30 day return policy.   Like most places, you end up losing shipping costs and possibly a small restocking fee for returns.

Also, putting a softer 1" or 2" below the convoluted topper, might give you the result you want as well.  So, you can try it both ways. 

Good luck!  Unfortunately trial and error is the only way you will really determine what you like.

After sleeping on 100% latex for 9 months, I decided that I needed a little relief from the "push back" of my top latex layer (3 inches of medium 24-28 ILD all Natural talalay).   I decided to try the 1 inch Sensus 5 lb memory foam from Overstock.com. It has made such a big difference that it's hard to believe only 1 inch could make such a change.  Although I don't sink into just 1 inch very much, it adds just enough pressure relief to make the bed feel more comfortable to me.  I do notice that it's a tad warmer than the latex, but with my wool/cotton mattress pad some of that extra heat is dissipated.  Plus, here in New Hampshire we don't mind a little extra warmth about 9 months of the year.

I agree with Sandman......maybe try adding just a 1 inch layer of memory foam at a time.

@Phoenix: It never would've occurred to me to try a latex-memory foam-latex combo, but it sounds like it could work.  I actually prefer the sensation of memory foam, it's the off-gassing I can't stand.  I'll keep your recommended set-up in mind in case the mem. foam over latex doesn't work out as anticipated.

@Sandman & Mark: The convoluted latex topper is 28 ILD blended talalay from FloBeds, approximately 2" at the peaks.  It's surprisingly supportive and a lot firmer than expected (maybe a cushion firm feel), so I feel fairly confident adding 2" of memory foam on top.  I checked out the 1" toppers at Overstock and it seems like all of them are cut shorter than standard mattress dimensions.  I have a problem with that because even though I'm only 5'6", I like extra arm room at the top of the mattress.  I'm a born sprawler.  Thanks to your recommendation, Sandman, I'm going to go with 4 lb. memory foam rather than the softer 3 lb.  The Aerus 4 lb. topper seems like a good fit for me since it's partially constructed from natural materials and undergoes some kind of special processing that captures emissions.  I hope that means little off-gassing; I guess I'll find out.  

@Sall: I like the idea of a 14 ILD latex topper...I guess that will be my next experiment if the memory foam doesn't work out.

Thanks everyone!